[PATCH] Cleanup patch for process freezing

1. Establish a simple API for process freezing defined in linux/include/sched.h:

   frozen(process)		Check for frozen process
   freezing(process)		Check if a process is being frozen
   freeze(process)		Tell a process to freeze (go to refrigerator)
   thaw_process(process)	Restart process
   frozen_process(process)	Process is frozen now

2. Remove all references to PF_FREEZE and PF_FROZEN from all
   kernel sources except sched.h

3. Fix numerous locations where try_to_freeze is manually done by a driver

4. Remove the argument that is no longer necessary from two function calls.

5. Some whitespace cleanup

6. Clear potential race in refrigerator (provides an open window of PF_FREEZE
   cleared before setting PF_FROZEN, recalc_sigpending does not check
   PF_FROZEN).

This patch does not address the problem of freeze_processes() violating the rule
that a task may only modify its own flags by setting PF_FREEZE. This is not clean
in an SMP environment. freeze(process) is therefore not SMP safe!

Signed-off-by: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/power/kernel_threads.txt

@@ -12,8 +12,7 @@ refrigerator. Code to do this looks like this:
 	do {
 		hub_events();
 		wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list));
-		if (current->flags & PF_FREEZE)
+		try_to_freeze();
-			refrigerator(PF_FREEZE);
 	} while (!signal_pending(current));
 
 from drivers/usb/core/hub.c::hub_thread()

Documentation/power/swsusp.txt

@@ -164,8 +164,7 @@ place where the thread is safe to be frozen (no kernel semaphores
 should be held at that point and it must be safe to sleep there), and
 add:
 
-            if (current->flags & PF_FREEZE)
+            try_to_freeze();
-                    refrigerator(PF_FREEZE);
 
 If the thread is needed for writing the image to storage, you should
 instead set the PF_NOFREEZE process flag when creating the thread.

arch/frv/kernel/signal.c

@@ -536,10 +536,8 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if (!user_mode(regs))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
+	if (try_to_freeze())
-		refrigerator(0);
 		goto no_signal;
-	}
 
 	if (!oldset)
 		oldset = &current->blocked;

arch/h8300/kernel/signal.c

@@ -517,10 +517,8 @@ asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if ((regs->ccr & 0x10))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
+	if (try_to_freeze())
-		refrigerator(0);
 		goto no_signal;
-	}
 
 	current->thread.esp0 = (unsigned long) regs;
 

arch/i386/kernel/io_apic.c

@@ -573,7 +573,7 @@ static int balanced_irq(void *unused)
 	for ( ; ; ) {
 		set_current_state(TASK_INTERRUPTIBLE);
 		time_remaining = schedule_timeout(time_remaining);
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 		if (time_after(jiffies,
 				prev_balance_time+balanced_irq_interval)) {
 			do_irq_balance();

arch/i386/kernel/signal.c

@@ -608,10 +608,8 @@ int fastcall do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if (!user_mode(regs))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
+	if (try_to_freeze)
-		refrigerator(0);
 		goto no_signal;
-	}
 
 	if (!oldset)
 		oldset = &current->blocked;

arch/m32r/kernel/signal.c

@@ -371,10 +371,8 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if (!user_mode(regs))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
+	if (try_to_freeze()) 
-		refrigerator(0);
 		goto no_signal;
-	}
 
 	if (!oldset)
 		oldset = &current->blocked;

arch/ppc/kernel/signal.c

@@ -705,8 +705,7 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
 	unsigned long frame, newsp;
 	int signr, ret;
 
-	if (current->flags & PF_FREEZE) {
+	if (try_to_freeze()) {
-		refrigerator(PF_FREEZE);
 		signr = 0;
 		if (!signal_pending(current))
 			goto no_signal;

arch/x86_64/kernel/signal.c

@@ -425,7 +425,7 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if (!user_mode(regs))
 		return 1;
 
-	if (try_to_freeze(0))
+	if (try_to_freeze())
 		goto no_signal;
 
 	if (!oldset)

drivers/block/pktcdvd.c

@@ -1251,8 +1251,7 @@ static int kcdrwd(void *foobar)
 			VPRINTK("kcdrwd: wake up\n");
 
 			/* make swsusp happy with our thread */
-			if (current->flags & PF_FREEZE)
+			try_to_freeze();
-				refrigerator(PF_FREEZE);
 
 			list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
 				if (!pkt->sleep_time)

drivers/ieee1394/ieee1394_core.c

@@ -1041,10 +1041,8 @@ static int hpsbpkt_thread(void *__hi)
 
 	while (1) {
 		if (down_interruptible(&khpsbpkt_sig)) {
-			if (current->flags & PF_FREEZE) {
+			if (try_to_freeze())
-				refrigerator(0);
 				continue;
-			}
 			printk("khpsbpkt: received unexpected signal?!\n" );
 			break;
 		}

drivers/ieee1394/nodemgr.c

@@ -1510,7 +1510,7 @@ static int nodemgr_host_thread(void *__hi)
 
 		if (down_interruptible(&hi->reset_sem) ||
 		    down_interruptible(&nodemgr_serialize)) {
-			if (try_to_freeze(PF_FREEZE))
+			if (try_to_freeze())
 				continue;
 			printk("NodeMgr: received unexpected signal?!\n" );
 			break;

drivers/input/gameport/gameport.c

@@ -439,7 +439,7 @@ static int gameport_thread(void *nothing)
 	do {
 		gameport_handle_events();
 		wait_event_interruptible(gameport_wait, !list_empty(&gameport_event_list));
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 	} while (!signal_pending(current));
 
 	printk(KERN_DEBUG "gameport: kgameportd exiting\n");

drivers/input/serio/serio.c

@@ -344,7 +344,7 @@ static int serio_thread(void *nothing)
 	do {
 		serio_handle_events();
 		wait_event_interruptible(serio_wait, !list_empty(&serio_event_list));
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 	} while (!signal_pending(current));
 
 	printk(KERN_DEBUG "serio: kseriod exiting\n");

drivers/macintosh/therm_adt746x.c

@@ -328,9 +328,7 @@ static int monitor_task(void *arg)
 	struct thermostat* th = arg;
 
 	while(!kthread_should_stop()) {
-		if (current->flags & PF_FREEZE)
+		try_to_freeze();
-			refrigerator(PF_FREEZE);
-
 		msleep_interruptible(2000);
 
 #ifndef DEBUG

drivers/md/md.c

@@ -2976,8 +2976,7 @@ static int md_thread(void * arg)
 		wait_event_interruptible_timeout(thread->wqueue,
 						 test_bit(THREAD_WAKEUP, &thread->flags),
 						 thread->timeout);
-		if (current->flags & PF_FREEZE)
+		try_to_freeze();
-			refrigerator(PF_FREEZE);
 
 		clear_bit(THREAD_WAKEUP, &thread->flags);
 

drivers/media/dvb/dvb-core/dvb_frontend.c

@@ -391,8 +391,7 @@ static int dvb_frontend_thread(void *data)
 			break;
 		}
 
-		if (current->flags & PF_FREEZE)
+		try_to_freeze();
-			refrigerator(PF_FREEZE);
 
 		if (down_interruptible(&fepriv->sem))
 			break;

drivers/media/video/msp3400.c

@@ -750,8 +750,7 @@ static int msp34xx_sleep(struct msp3400c *msp, int timeout)
 #endif
 		}
 	}
-	if (current->flags & PF_FREEZE)
+	try_to_freeze();
-		refrigerator(PF_FREEZE);
 	remove_wait_queue(&msp->wq, &wait);
 	return msp->restart;
 }

drivers/media/video/video-buf-dvb.c

@@ -62,8 +62,7 @@ static int videobuf_dvb_thread(void *data)
 			break;
 		if (kthread_should_stop())
 			break;
-		if (current->flags & PF_FREEZE)
+		try_to_freeze();
-			refrigerator(PF_FREEZE);
 
 		/* feed buffer data to demux */
 		if (buf->state == STATE_DONE)

drivers/net/8139too.c

@@ -1606,7 +1606,7 @@ static int rtl8139_thread (void *data)
 		do {
 			timeout = interruptible_sleep_on_timeout (&tp->thr_wait, timeout);
 			/* make swsusp happy with our thread */
-			try_to_freeze(PF_FREEZE);
+			try_to_freeze();
 		} while (!signal_pending (current) && (timeout > 0));
 
 		if (signal_pending (current)) {